Using Gemstones as Currency

Gemstones may not be a unit of weight because the weight by itself doesn't necessarily tell us how valuable that gemstone is. High quality stones can actually achieve more quality or less quality depending on how well that stone is carved. Another option we're all familiar with is paper money but it is easier to carry around large sums than coins. Bills are typically for larger numbers such as dollars whereas the coins are for smaller amounts like cents. One amber piece equaling 10 cents, 10 amber pieces equals one jade, 10 jade is one amethyst and 10 amethyst is one opal. Of course you are free to make up your own hierarchy of this. We could do something like